Electronic devices play integral roles in manufacturing, healthcare, commerce, social interaction, entertainment, and communication. For example, most people consider their smart phone a critical part of their daily lives. Electronic devices also enable the computer server farms that provide cloud-based, distributed computing functionality for commerce and social interaction. Further, devices with computing power are embedded in many different types of modern equipment, from medical devices to household appliances and from vehicles to industrial tools. Thus, electronic devices are manufactured in a multitude of sizes, form factors, and capabilities for an even greater array of purposes. One particularly prominent purpose for electronic devices is communication, including communication over longer distances.
Prior to the development of electronic devices, long-distance communication was generally limited to the physical transport of a letter by a human being. Other options included sending up smoke signals or recruiting a pigeon to carry a short letter. The former option is limited to short distances and is subject to the whims of the weather, and the latter option has reliability issues that are self-evident. Fortunately, the invention of the telegraph ushered in the age of reliable long-distance communication using electrical signals that encoded the written word using, e.g., a Morse code for each letter. Eventually, telegraph technology was upgraded to telephone technology so that people could simply speak to one another using electrical signals that traversed great distances. Both telegraph and telephone technology, however, require a wire that is extended between both parties to a communication.
The next step in the evolution of communication involved harnessing electromagnetic (EM) waves that travel in free space without using a wire. However, EM waves generally travel in a straight line, so they could not easily cover great distances around a curved earth. One exception to this is shortwave EM signals. Shortwave EM signals still travel in straight lines, but they reflect off a layer of the earth's atmosphere called the ionosphere. Shortwave EM signals can therefore be reflected past the earth's horizon to enable communication across thousands of miles. Unfortunately, communicating with shortwave EM signals typically involves using antennas that are many tens of feet tall. These are expensive and impractical for mobile communication. To enable portability, citizen band (CB) radios and walkie-talkies were developed for mobile use. As early as the 1960s and 1970s, CB radios and walkie-talkies could be produced in a portable or even hand-held form. Unfortunately, communication with either of these portable devices was limited to just a few miles.
By the 1980s, communication using electrical or EM signals was generally divided into using fully-wired technology or fully-wireless technology, especially for consumers and in other low-cost scenarios. For example, telephones enabled long-distance voice communication, but telephone technology was still generally limited to wired connections. Portable radios, on the other hand, used EM waves to establish wireless connections, but voice communications with these consumer-level devices used EM waves that were generally limited to no more than a few miles. To merge these two technologies and achieve some benefits of both, cellular technology was created. Cellular technology can be implemented using a communication network that combines both a wireless network and a wired network. As a result, cellular technology enables mobile electronic devices to be used to make long-distance communications.
With cellular technology, a communication between two people usually has both a wireless portion and a wired portion. A portion of the communication that is near one party is instituted using a wireless connection between a mobile phone and a base station, which is part of a cellular or wireless network of a larger communication network. This wireless connection typically extends from a few feet to a few miles. The communication network also includes or is coupled to a wired network. The base station can therefore continue the communication using a wired connection over the wired network. The wired network can extend from hundreds of feet to thousands of miles. If the other party is also using a mobile phone, the communication can be converted back to another wireless portion and routed to the other party using another wireless connection.
To enable cellular technology to work across a wide geographic region, many base stations are distributed across the region to enable a wireless portion of a communication to be established at different locations. Each of these base stations is typically able to support multiple users by simultaneously establishing multiple wireless connections with respective ones of multiple mobile phones. Thus, by the 1990s, cellular technology enabled voice calls to be made using a communication that included both a wireless connection and a wired connection. To expand the ability to communicate with more than voice using cellular technology, cellular systems were augmented to include an ability to communicate textually. Such communication used text messages, which were called short message service (SMS) messages. This continued efforts to enable mobile phones and other electronic devices to send and receive data, as well as exchange voice communications.
Communication of data, in addition to voice, became feasible with the development of Second Generation (2G) wireless networks. Data communication was not meaningful for most purposes, however, until Third Generation (3G) wireless networks were deployed. 3G wireless networks enabled mobile phone users to send and receive simple emails and access basic web pages without experiencing lengthy delays. However, Fourth Generation (4G) networks, such as those based on a Long-Term Evolution (LTE) standard, truly enabled the data-based wireless services that users enjoy today. For example, with a smart phone operating on a 4G network, a user can now make video calls in addition to voice calls. Additionally, users can surf the web without appreciable constraints and can receive real-time, turn-by-turn navigational directions. Further, users can stay up-to-date on social media postings, upload their own images or even videos, and watch high-definition video, all while on-the-go.
To accommodate these existing services, wireless networks are already expected to handle immense quantities of data with little to no appreciable delays. However, newer services are primed to demand even more from cellular wireless networks. Users will expect greater data bandwidth and even less delay, called latency, to accommodate such services. These new services include high-bandwidth applications like ultra-high definition (UHD) video that is delivered wirelessly from a streaming video service to a mobile device. Such services also include low-latency applications like autonomous-driving vehicles that communicate with each other to avoid accidents and that can therefore operate more safely if provided nearly instantaneous data communication capabilities. Some applications, like virtual reality (VR), will demand data delivery that provides a combination of both high-bandwidth and low-latency. Further, there is the ongoing development of the Internet of Things (IoT), which involves providing wireless communication capabilities to everything from medical devices to security hardware and from refrigerators to speakers. The deployment of IoT devices means hundreds of billions to trillions of new devices will soon be trying to communicate wirelessly.
Current 4G wireless networks are not expected to be able to handle the data bandwidth and latency specifications for these new applications. Accordingly, to enjoy these new applications, new wireless technology is being developed. This Fifth Generation (5G) wireless network technology will adopt higher frequency EM waves (e.g., 6 GHz to 100 GHz for millimeter wave (mmW) wireless connections) to attain higher data bandwidth in conjunction with lower latency. These new applications and higher EM frequencies, however, introduce new and different challenges that are yet to be overcome.
For example, with the multitude of IoT devices that are coming on-line, the EM spectrum that is allocated to cellular wireless usage will be shared among many more wireless connection endpoints. Also, with the mmW EM signaling that will be used in some wireless networks, including 5G cellular networks, wireless signals are attenuated more quickly. More specifically, mmW EM signals are attenuated more quickly by air molecules and other environmental factors, such as humidity or physical obstructions, as compared to those signaling frequencies used in earlier generations of wireless networks. Consequently, mmW EM signals are incapable of traveling as far through the atmosphere before a quality thereof is reduced to a level at which the information in the wireless signal is lost or otherwise becomes unusable. To address these issues, engineers and manufacturers are striving to create new wireless signaling technologies that can enable utilization of these GHz frequencies in a cellular wireless network, including those operating in accordance with a 5G wireless network standard.
This background description is provided to generally present the context of the disclosure. Unless otherwise indicated herein, material described in this section is neither expressly nor impliedly admitted to be prior art to the present disclosure or the appended claims.